Isn't there some verse somewhere about how Christians aren't supposed to enslave other Christians?
No there is not and in fact quite the opposite. There is a book in the New Testament (a letter really) written by the Apostle Paul to a Christian called Philemon. Paul was writing from prison and apparently his cellie was this dude called Onesimus (who was a recent convert to Christianity) who was owned by Philemon. Paul asks Philemon to free Onesimus so he could accompany Paul on his journeys across the Mediterranean spreading the Gospel.
What is important about this is that Paul had crazy amounts of authority and could even challenge the Apostle Peter on issues and in this letter he never tells Philemon that as a Christian he had any actual obligation to release Onesimus and has to request of Philemon (as a favor to Paul) that he allow Onesimus his freedom so he could accompany Paul. The request is framed like Paul was asking Philebus to give him a boat he has drydocked and doesn't really use because Paul could make better use of it. If Philemon had some kind of religious obligation as a Christian not to own Onesimus, then Paul would have been rebuking him and just straight up telling him to release Onesimus and threatening possible sanctions if he refused. Onesimus' manumission was a donation to the Church like money or a piece of land.
I also feel I should mention that this letter (epistle) wasn't a piece of private correspondence either, it was to be read publicly to the house-congregation that Philemon hosted and was circulated and publicly read at other churches as well before making its way into the Christian canon. Paul isn't shy about lighting people the fuck up in these epistles either, so I don't think one could meaningfully argue that Paul was just being diplomatic because he just wasn't diplomatic when it came to issues of orthopraxis. He literally excommunicated a group of Christians whose beliefs were exactly his except they wanted Gentile converts to Christianity to undergo circumcision; that little "addition" was enough to get them consigned to the fires of hell.
I seem to recall that being a whole controversy with the Kingdom of the Kongo back when the African slave trade was becoming a thing, because the king converted and made everyone under his rule convert too, then got butthurt that slave traders were still nabbing and cramming his people on the boats with everyone else (before you feel too sorry for him, keep in mind that he was totally cool with enslaving non-Kongolese Africans, which he actively participated in and was one of the rulers who initiated slave trading with the Europeans), so he played the Bible card. Then some clever true and honest (((euros))) argued a loophole about how Africans didn't count due to racial theories or something, and it was basically ignored from then on because there was way too much money to be made to be pious about the whole thing.
I'm going purely off memory here, but I think in the case of the Kongo, one of the justifications used was that the Kongolese people were proper "Hammites" and thus condemned to a life of servitude. In the book of Genesis there is this strange story about Noah; after he and his family survive the flood he basically disembarks, thanks God with an altar sacrifice, then plants a vineyard, harvests his grapes, and gets shitfaced on homebrewed wine and blacks out in his tent.
I'll skip the discourse on semitic philology but some of Noah's sons enter the tent (and depending on your interpretation) proceed to either; (a) observe their father's naked body causing him shame, (b) anally penetrate Noah causing him shame, or (c) castrate Noah causing him shame. Noah doesn't take kindly to this and puts a curse on his son Ham by saying his descendants will serve the descendants of his brothers. Through ancient folk-etymology the descendants of Ham or "Hammites" have been taken be groups of exploitable people in the Levant to Sub-Saharan Africa.
The Bible permits and regulates slavery and doesn't really forbid
in toto, but most cultures in Antiquity were the same. No less a paragon of reason and the greatest systemizer of human knowledge Aristotle thought slavery was just a natural state for some humans. If you go back and read the written debates between American Abolitionists and Slavery Advocates, I think you'll see the Slavery Advocates carry the day when it came to arguing about scripture. Once it actually became illegal the fight was over because Christians are instructed to follow the law if it doesn't impinge orthodoxy and worship, which slavery doesn't.
Nick is about as literate as Sargon, which is to say I'd be genuinly impressed if he actually went through the mechanical process of reading a non-fiction book. I mean in that clip where he talks about women and history he actually resorts to telling a story from his "History AP class" in Highscool lol.
